So this heyous crank puller set is one of those specific bike tools you don't need often, but when you do, you're really glad to have it! The 2-piece set gives you both the 1.3cm and 1.5cm sizes, covering pretty much any crank removal situation you'll encounter. The carbon steel construction feels solid and durable - this isn't some flimsy tool that's going to strip or break when you apply pressure. The function is straightforward but essential - it removes crank arms from the bottom bracket spindle without damaging the threads or components. The detachable head design makes it suitable for conical types, which is important since different bike brands use slightly different crank designs. You will need an adjustable wrench to use it properly, but that's standard for most bike tools. I've used this for maintenance tasks like replacing bottom brackets, installing new cranksets, or just doing deep cleaning on drive train components. The threads are cut cleanly and engage smoothly without cross-threading issues. For the price, having both sizes available means you're covered for most modern bicycles whether you're working on your own bike or helping friends with theirs. It's one of those tools that pays for itself the first time you need to remove cranks instead of paying a bike shop to do it. Whether you're a home mechanic maintaining your own bikes or someone who works on multiple bicycles regularly, this crank puller set provides reliable performance without the professional tool price tag.